can't find the "low_io_sectors" and "high_io_sectors" in /proc/sys/vm

[richeal75]

hello ,

Now I want to adjust kernel parameter as below:
echo 2000 > /proc/sys/vm/low_io_sectors
echo 4000 > /proc/sys/vm/high_io_sectors

but i can't find them in /proc/sys/vm .


os: redhat AS 2.1
my kernel: 2.4.9-e3smp
url:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=85231

[Gopi Sekar · Accepted solution]

i check on my 2.6 kernel but couldnt find one either. but i think they have changed a lot from 2.4 to 2.6, nevermind.

check up through sysctl, try one of these to find which one succeeds.

sysctl proc.sys.vm.low_io_sectors
sysctl proc.stat.low_io_sectors
sysctl proc.sys.low_io_sectors

if any of them succeed and outputs the value then set them using sysctl -p, for further information check 'man sysctl'

Regards,
Gopi

[Stuart Browne]

Direct quote from the URL you posted:

What we have done in 2.4.9-e.12

i.e. a different kernel revision. Update to at least that kernel revision, and try again.

I know that option isn't available on my FC box running a 2.4 series kernel.

[richeal75]

Gopi Sekar & Stuart Browne :

thanks for yours help !

As I'm beginner of Redhat Linux , I want to know how to upgrade my Redhat AS 2.1 with kernel 2.4.9-e3smp to 2.4.9-e12smp.

pls advise a simple way !

thanks again !

[Gopi Sekar]

The simplest way would be to use up2date utility with RHN subscription. then you can use this utility to update all the packages in your system including kernel or you can specify which paackage you want update and get them updated.

Also the 2.4.9-e12 kernel is outdated and there is a new kernel which includes this fix along with few other fixes, check out the following link about it.
http://rhn.redhat.com/errata/RHSA-2005-283.html

the above link also gives instruction on how to upgrade the kernel from command line.

anyway even to download the kernel manually you need to have RHN subscription.

Regards,
Gopi

[richeal75]

Hello ,

I can find "low_io_sectors" and "high_io_setcotrs" in /proc/sys/vm after i upgrade kernel from 2.4.9-e3 to 2.4.9-e62

and then I adjust them as below:

echo 2000 /proc/sys/vm/low_io_sectors
echo 4000 /proc/sys/vm/high_io_sectors

and then result is ok as below

2000 /proc/sys/vm/low_io_sectors
4000 /proc/sys/vm/high_io_sectors

and I run " more /proc/sys/vm/low_io_sectors"
but I find the value is not changed

why ?

[Gopi Sekar]

you forgot to add '>' symbol

it should be like this:

echo 2000 > /proc/sys/vm/low_io_sectors


Hope this helps,
Gopi